The present invention resides in a device for continuous, horizontal casting of metals, particularly aluminum and its alloys, using a casting trough, a holding furnace or the like having in one wall near the bottom a tapping hole which connects up to a nozzle opening situated in the lower part of a disc-shaped nozzle by means of which the molten metal is transferred to the mold.
The components used for the melt transfer system in horizontal casting are generally made of refractory materials in some versions in combination with nozzles made of graphite or another suitable material, or of insulated or plasma coated metal. The outlet for the melt is situated near the floor of the holding furnace or casting trough and connects up with the opening in the lower part of the nozzle; the exceptions here are systems for casting special shapes--for example U-shaped rails, tubes, box-shaped sections--and the central pouring system with built-in baffle plates.
When casting round ingots, there is a channel-shaped part with refractory lining connected up to the nozzle which is in the form of a disc with a circular opening in it. The metal leaves the trough via that nozzle on its way to the mold, the nozzle opening forming an abrupt transition, as a result of its position with respect to the inner face of the mold. Such systems can be employed only for certain products which have to meet normal quality standards since there are frequently surface flaws such as, for example, differences in the quality of the upper and lower surfaces of the ingot, open or concealed shuts,-13 in particular in the upper region--laps, bleeding, roughness and surface segregation. Inside the ingot there can be clusters of particles, a so-called marble structure, internal cracks and dross. One can also find coring, an inhomogeneous structure in the form of onion-like solidification rings, an inhomogeneous sump with striations, and a tendency for twinned or feathery crystals to form. It is therefore impossible to guarantee uniform quality.
In the U.S. Pat. No. 3,381,741 a simple arc-shaped slit is disclosed as a nozzle-like opening in the wall of a casting trough, which however also suffers from the above mentioned and further disadvantages.